So apart from continental drift which is about 6cm north per year (or roughly 0.01 of a second for those mapping boffins out there), can someone please explain how WGS 84 co-ords of a known position changes over time? (ie the survey was originally conducted in the WGS 84 datum)
Most aviation co-ords are rounded to the nearest decimal of a minute or whole seconds. From my previous mapping experience, the 5 year requirement for resurveys was more about checking relative bearings and re applying an updated magentic variation, as the official magvar EPOCH is updated every 5 years by Geosciences Australia, and thats why revalidation is required.
I know the type A charts are done (or are supposed to be done) every 5 years and they recheck the coords of navaids, thlds etc. But as for the co-ords actually changing, I have never experienced it.
Alpha